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United States Patent 3,125,501 METHOD OF PREPARING FiNELY-DIVIDED MATERIAL jdwin C. Knowles, Poughkeepsie, Frederic C. McCoy,

This invention relates to a method of preparing powdered material, and, more particularly, to a method of preparing finely-divided solid particles of material from a solution of the material.

This invention has as its object to provide a method of preparing finely-divided material by forming a solid adduct or complex of the material from a solution of the material, and subsequently dissociating the complex to release the complexed material in a fine powder form.

In accordance with our invention, finely-divided mate rial is prepared from a material selected from the group consisting of aliphatic hydrocarbons, and derivatives of aliphatic hydrocarbons, having a straight chain portion of not less than 8 carbon atoms and capable of forming a solid complex, as described more fully hereinbelow. 'Ihe aliphatic hydrocarbon or the derivative thereof undergoing treatment may normally be liquid at room temperature and atmospheric pressure or solid in which case the material is dissolved initially in a. suitable liquid solvent. The hydrocarbon or derivative thereof, as a solution, is contacted with a complexing agent in the presence of a polar solvent to form a solid complex which separates from the remaining solution. The solid complex is con tacted with a liquid which dissociates the solid complex and which is relatively cool in comparison with the melting point of the material being prepared in finely-divided form. Upon agitation of the resulting mixture, the aliphatic hydrocarbon or the derivative thereof separate from the mixture as a finely-divided material which is recovered by filtration, centrifuging, or the like.

Materials found particularly suitable for our invention, and which therefore may be prepared in finely-divided form, include those from the group consisting of aliphatic hydrocarbons and derivatives of aliphatic hydrocarbons having a straight chain portion of not less than 8 carbon atoms, and capable of forming a solid complex with the complexing agent. The straight chain portion may be saturated or contain an unsaturated linkage. A wide variety of terminal groups or radicals may be provided at one end of the straight chain portion including aromatic, cycloparaffinic and oleiinic groups, as well as alcohol, aldehyde, ketone, halogen and oarboxyl groups. Derivatives of aliphatic hydrocarbons may include, for example, the fatty acids such as stearic acid, oleic acid, palmitic acid and linoleic acid, or their salts such as zinc stearate, etc.; the aliphatic alcohols, such as stearyl alcohol and palmityl alcohol; the aliphatic amines and amides, such as stearyl amine and stearamide; and the halogenated derivatives.

When the hydrocarbon or derivative thereof undergoing treatment is normally solid at room temperature and atmospheric pressure, the material is dissolved initially in a liquid solvent which desirably includes the various normally liquid petroleum hydrocarbons or petroleum fractions in the naphtha boiling range, such as petroleum hydrocarbons having a boiling point or range of from about 125 to 425 F. Aromatic hydrocarbons, for example, benzene, toluene and the xylenes, are preferred. The liquid solvent should be substantially devoid of those compounds or hydrocarbons which form a complex with ice urea or thioure-a under the conditions of complex formation or complex dissociation.

It is well recognized that a number of aliphatic hydrocarbons and derivatives of aliphatic hydrocarbons upon treatment with urea or thiourea or their analogs form a solid crystalline complex. In practicing our invention, the complexing agent selected from the group consisting of urea and thiourea is initially dissolved in a polar solvent, e.g. an alcohol, which is then added to a solution of the aliphatic hydrocarbon or a derivative of an aliphatic hydrocarbon having a straight chain portion of not less than 8 carbon atoms. The solid complex formed separates from the remaining solution and may be recovered by any suitable means, such as filtering, decanting, centrifuging, or the like. The complexing action desirably proceeds within a temperature range of between 40 F. and F., although higher temperature-s may be employed depending to some extent upon the melting point of each component making up the mixture.

The solid complex is contacted with a liquid, such as water, which dissociates the solid complex and the resulting mixture is agitated to obtain intimate contact between the complex and water. The water dissolves the complexing agent, and discrete particles of the hydrocarbon or derivative thereof undergoing treatment separate out. The Water is maintained at a relatively cool temperature, preferably not less than 10 cooler than the melting point of the final product prepared in powdered form. It is advantageous to employ an excess of water in order that the solid complex may be completely submerged in the aqueous mixture. The mixture may be agitated as the solid complex is contacted with the water, or all the solid complex may be added to the Water and the mixture then agitated. Preferably, intense agitation is employed which may be satisfactorily accomplished by high speed stirring as, for example, with paddle stirrers or impeller stirrers rotating at relatively high speeds. This treatment dissociates the solid complex into discrete particles of the hydrocarbon or derivative undergoing treatment which separate from the remaining aqueous mixture in finelydivided form, the complexing agent being dissolved by the water. The line particles of the hydrocarbon or derivative may be separated from the remaining aqueous mixture by filtration, and dried by conventional means, if desired, to recover the hydrocarbon or derivative in powder form.

The liquid employed in dissociating the solid complex is dependent to some extent upon the melting point of the material undergoing treatment. Where the aliphatic hydrocarbon or derivative being prepared in finely-divided form are normally solid at room temperature and atmospheric pressure, water may be conveniently and economically used as the complex dissociating liquid. This invention also contemplates preparation of finely-divided materials which are normally liquid, or, conversely, solid at relatively low temperatures. in this event, it may be desirable, or often necessary, to use a complex dissociating liquid having a relatively low freezing point as compared to that of water. Thus, organic liquids, particularly the alkanols and ketones having 1 to 6 carbon atoms and aqueous mixtures thereof, and liquid ammonia, may be advantageously employed. Examples of the alkanols include methanol, ethanol, propanol, isopropanol, n-butanol, etc., and the ketones may include acetone, methylet-hyl ketone, ethylpropyl ketone, methylisobutyl ketone, etc. However, the invention is particularly applicable in the preparation of finely-divided materials which are normally solid, and therefore the invention has been described in more detail in connection with the use of water as the ,3 particular complex dissociating liquid, although it is understood that other liquids are applicable.

The polar solvent in which the complexing agent is dissolved includes the normally liquid polar aliphatic organic compounds. This includes for example, the allcanols, such as methanol, ethanol, p ropanol, isopropanol, isobutanol, n-butanol, tertiary butyl alcohol; the various ketones, such as acetone, methylethyl ketone, ethylpropyl ketone, methyl propyl ketone, methyl n-butyl ketone, methylisobutyl ketone; aqueous solutions of the foregoing; and water. In general, any normally liquid polar aliphatic organic compound containing from 1 to 6 carbon atoms per molecule can suitably be employed. Other polar solvents which may suitably be employed include the low boiling amines such as ethylamine; the low boiling mercaptans such as ethyl mercaptan; the olefinic glycols such as monoethylene glycol; the allcanolamines such as ethanolamine; or mixtures thereof such as aqueous solutions of methanol and monoethylene glycol.

Where desired, a minor amount of a suitable surface active agent such as the sodium sulfonates may be incorporated in the solution of the material being prepared in powdered form. The surface active agent facilitates separation of the finely-divided hydrocarbon or derivative from the aqueous mixture, and the quantity of water entrained by the recovered product is reduced substantially. The choice of surface active agent is determined largely by the materials employed in the process, and may be anionic, cationic or non-ionic. About 0.01 to 0.2% by weight of surface active agent may be incorporated, preferably by dissolving the agent in the polar solvent, but smaller or larger amounts may be used where desired.

In addition, a small amount of a micro-dimensional silica powder which is hydrophobic may be incorporated in the powdered product. The amount of silica powder used depends somewhat upon the hydrocarbon or derivative being treated, but generally about 0.2 to 3% by weight is satisfactory. The silica powder facilitates in the separation of the finely-divided hydrocarbon material from the aqueous mixture, and further assists in maintaining the powdered hydrocarbon or derivative in a dry condition and therefore freelowing.

Our invention is further illustrated by the following examples.

Example 1 112 grams of paraffin wax having a melting point range of 124-130" F. were dissolved in 1500 mls. of benzene. A solution containing 1000 mls. of methanol saturated with urea was added to the wax-benzene solution with stirring, the temperature of the mixed solutions being about 80 F. The resulting wax-urea complex was filtered, and the filter cake washed with pentane and dried at room temperature. The yield was 147 grams. A 50 gram portion of the solid complex of wax and urea was added to 400 ml. of water at about 60 F. The mixture was vigorously agitated in a Waring Blendor, and finelydivided wax separated out from the aqueous mixture. Upon filtration, 13 grams of powdered paramn wax were recovered having a very fine particle size, many individual particles measuring 0.02-0.05 micron in largest dimension with some aggregates up to 20 microns. The powdered wax melted at about 130 F.

Example 2 56 grams of stearic acid were dissolved in 750 mls. of benzene, and the stearic acid complexed with urea as in Example 1. 38 grams of the complex were decomposed in cold water, as above, yielding 26 grams of fine powdered stearic acid.

Example 3 56 grams of stearyl amine were substituted for the wax of Example 1. 40 grams of the amine-urea complex 41, were treated in cold water, as above, producing 10 grams of stearyl amine in fine powdered form.

Example 4 50 grams of the wax-urea complex of Example 1 were stirred with 400 ml. cold water in the Waring Blendor for two minutes. Stirring was then interrupted, and about 0.3 gram of hydrophobic silica powder was added, and the mixture again stirred for one minute. The aqueous mixture filtered readily, and the powdered wax remained free-flowing over a long period of time.

Example 5 56 grains cetane were added with stirring to 500 ml. methanol saturated with urea. The resulting cetane-urea complex was filtered, washed with pentane and dried at room temperature. 24 grams of this complex were added to 400 ml. of ice-water and stirred vigorously in the Waring Blendor for 30 seconds. After the stirring ceased. a line white powdered cetane rose to the surface of the aqueous mixture. The filtration equipment was chilled. and the powdered cetane recovered by filtration. The powdered product was stored in a refrigerator for subsequent use.

Example 6 56 grams n-octadecyl alcohol (stearyl alcohol) were substituted for the wax of Example 1. The alcohol was complexed with urea, and 35 grams of the complex were subsequently decomposed in 400 ml. of cold water, as in Example 1. 20 grams of n-octadecyl alcohol were recovered having a melting point of 56 C.

Example 7 30 grams of wax-urea complex prepared as in Example 1 and 0.1 gram of dodecylbenzene sulfonic acid, as a surface active agent, were added to 300 ml. of cold water. The aqueous mixture was stirred in a Waring Blendor for 5 minutes. A fine powdered wax was recovered upon filtration.

In many instances, the fine powder materials produced in accordance with our invention are relatively more reactive than coarse materials and therefore may be useful where reactivity is important. Powdered wax may be used as a temporary binder in the dry state at low temperatures in forming a green mold for powdered refractory materials or powdered metals.

We claim:

1. A method of preparing finely-divided powder from a material selected from the group consisting of aliphatic hydrocarbons and derivatives of aliphatic hydrocarbons having a straight chain portion of not less than 8 carbon atoms and capable of forming a solid complex with a complexing agent selected from the group consisting of urea and thiourea, comprising contacting a solution of said material with said complexing agent in the presence of a polar solvent for said complexing agent, forming a solid complex comprising said material and said complexing agent, separating said solid complex from the remaining solution, contacting said solid complex with water containing between about 0.01 and 0.2% by weight of a surface active agent at a temperature below that of the melting point of said material, subjecting the resulting mixture to agitation whereby said material separates out of said resulting mixture as finely-divided solid, and recovering said finely-divided solid.

2. The process of claim 1 in which the surface active agent is dodecylbenzene sulfonic acid.

3. The process of claim 1 in which powdered silica is added to the recovered finely divided material in an amount sufiicient to maintain said material free flowing.

4. The process of claim 3 in which the powdered silica is added in an amount between about 0.2 and 3% by weight of the recovered finely divided material.

(References on following page) 5 6 References Cited in the file of this patent FOREIGN PATENTS UNITED STATES PATENTS 556,407 Germany Aug. 8, 1932 2,300,134 Priewe "061. 27, 1942 511,15 Canada 1955 2,642,377 Fetterly June 16, 1953 2,661,317 Skeltcm et a1. D66. 1, 1953 5 OTHER REFERENCES 2,689,845 Dinerstein Se t 21, 1954 Rogers et al.: Petroleum Refinelr, v01. 36, No. 5, 2,746,876 Mills May 22, 1956 M y 195 pp- 217-220, 2,834,716 Champagnat et 211, V May 13, 1958 

1. A METHOD OF PREPARING FINELY-DIVIDED POWDER FROM A MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC HYDROCARBONS AND DERIVATIVES OF ALIPHATIC HYDROCARBONS HAVING A STRAIGHT CHAIN PORTION OF NOT LESS THAN 8 CARBON ATOMS AND CAPABLE OF FORMING A SOLID COMPLEX WITH A COMPLEXING AGENT SELECTED FROM THE GROUP CONSISTING OF UREA AND THIOUREA, COMPRISING CONTACTING A SOLUTION OF SAID MATERIAL WITH SAID COMPLEXING AGENT IN THE PRESENCE OF A POLAR SOLVENT FOR SAID COMPLEXING AGENT, FORMING A SOLID COMPLEX COMPRISING SAID MATERIAL AND SAID COMPLEXING AGNET, SEPARATING SAID SOLID COMPLEX FROM THE REMAINING SOLUTION, CONTACTING SAID SOLID COMPLEX WITH WATER CONTAINING BETWEEN ABOUT 0.01 AND 0.2% BY WEIGHT OF A SURFACE ACTIVE AGENT AT A TEMPERATURE BLEOW THAT OF THE MELTING POINT OF SAID MATERIAL, SUBJECTING THE RESULTING MIXTURE TO AGITATION WHEREBY SAID MATERIAL SEPARATES OUT OF SAID RESULTING MIXTURE AS FINELY-DIVIDED SOLID, AND RECOVERING SAID FINELY-DIVID SOLID. 